Authors:
Duan Y, Zhang HZ, Bu RF. Correlation between cellular phone use and epithelial parotid gland malignancies. Int J Oral Maxillofac Surg. Apr 5, 2011. Ahead of print.Introduction
Most epidemiological studies of cell phone use and cancer were focused on intracranial tumors. Few studies examined the association between cell phone use and parotid gland tumors, and the results of these studies are controversial.

Objective
The objective was “to investigate the effect of cellular phone use on the risk of epithelial parotid gland malignancy, especially mucoepidermoid carcinoma of the parotid gland”.

Methods
This case-control study included data on 136 patients who underwent surgery for parotid gland tumors at the Oral and Maxillofacial Surgery Department of the Chinese PLA General Hospital in Beijing between January 1993 and March 2010. All cases were histologically or cytologically confirmed epithelial parotid gland malignancies. Controls were 2,051 patients with non-malignant conditions treated at the Department during the same period. Data on cell phone use, other lifestyle and socio-demographic characteristics were obtained from personal or telephone interviews.

Results, Interpretation and Conclusion
There was an indication of a dose-response relationship between cell phone use and the risk of parotid gland malignancies. Thirteen cell phone use variables were associated with epithelial parotid gland malignancies in the multivariate analysis. The three variables with the greatest odds ratios (ORs) were: more than 42,000 calls since first use (OR=15.4; 95% CI 13.3-17.4), use for more than 9-10 years (OR=7.7; 95% CI 6.2-9.2), and average daily use for more than 2.5 hours (OR=6.0; 95% CI 1.5-24.5). Because there was no association between the preferred side of cell phone use and the risk of epithelial parotid gland malignancies, the authors do not make any causal inferences. They indicate the possibility of bias in their study and suggest that “additional large-scale studies, especially those with a prospective design, be performed to reduce the sources of bias and to confirm the significance of the present results”.